1 /*
2 * SPDX-FileCopyrightText: 2015-2021 Espressif Systems (Shanghai) CO LTD
3 *
4 * SPDX-License-Identifier: Apache-2.0
5 */
6 #include "sdkconfig.h"
7
8 #include "bootloader_flash_priv.h"
9 #include "bootloader_sha.h"
10 #include "bootloader_utility.h"
11 #include "esp_log.h"
12 #include "esp_image_format.h"
13 #include "esp_secure_boot.h"
14 #include "spi_flash_mmap.h"
15 #include "esp_fault.h"
16 #include "esp32/rom/sha.h"
17 #include "uECC_verify_antifault.h"
18
19 #include <sys/param.h>
20 #include <string.h>
21
22 static const char *TAG = "secure_boot";
23
24 #ifdef CONFIG_SECURE_SIGNED_APPS_ECDSA_SCHEME
25 extern const uint8_t signature_verification_key_start[] asm("_binary_signature_verification_key_bin_start");
26 extern const uint8_t signature_verification_key_end[] asm("_binary_signature_verification_key_bin_end");
27
28 #define SIGNATURE_VERIFICATION_KEYLEN 64
29
esp_secure_boot_verify_signature(uint32_t src_addr,uint32_t length)30 esp_err_t esp_secure_boot_verify_signature(uint32_t src_addr, uint32_t length)
31 {
32 uint8_t digest[ESP_SECURE_BOOT_DIGEST_LEN];
33 uint8_t verified_digest[ESP_SECURE_BOOT_DIGEST_LEN] = { 0 }; /* ignored in this function */
34 const esp_secure_boot_sig_block_t *sigblock;
35
36 ESP_LOGD(TAG, "verifying signature src_addr 0x%x length 0x%x", src_addr, length);
37
38 esp_err_t err = bootloader_sha256_flash_contents(src_addr, length, digest);
39 if (err != ESP_OK) {
40 return err;
41 }
42
43 // Map the signature block
44 sigblock = (const esp_secure_boot_sig_block_t *) bootloader_mmap(src_addr + length, sizeof(esp_secure_boot_sig_block_t));
45 if(!sigblock) {
46 ESP_LOGE(TAG, "bootloader_mmap(0x%x, 0x%x) failed", src_addr + length, sizeof(esp_secure_boot_sig_block_t));
47 return ESP_FAIL;
48 }
49 // Verify the signature
50 err = esp_secure_boot_verify_ecdsa_signature_block(sigblock, digest, verified_digest);
51 // Unmap
52 bootloader_munmap(sigblock);
53
54 return err;
55 }
56
esp_secure_boot_verify_signature_block(const esp_secure_boot_sig_block_t * sig_block,const uint8_t * image_digest)57 esp_err_t esp_secure_boot_verify_signature_block(const esp_secure_boot_sig_block_t *sig_block, const uint8_t *image_digest)
58 {
59 uint8_t verified_digest[ESP_SECURE_BOOT_DIGEST_LEN] = { 0 };
60 return esp_secure_boot_verify_ecdsa_signature_block(sig_block, image_digest, verified_digest);
61 }
62
esp_secure_boot_verify_ecdsa_signature_block(const esp_secure_boot_sig_block_t * sig_block,const uint8_t * image_digest,uint8_t * verified_digest)63 esp_err_t esp_secure_boot_verify_ecdsa_signature_block(const esp_secure_boot_sig_block_t *sig_block, const uint8_t *image_digest, uint8_t *verified_digest)
64 {
65 ptrdiff_t keylen;
66
67 keylen = signature_verification_key_end - signature_verification_key_start;
68 if (keylen != SIGNATURE_VERIFICATION_KEYLEN) {
69 ESP_LOGE(TAG, "Embedded public verification key has wrong length %d", keylen);
70 return ESP_FAIL;
71 }
72
73 if (sig_block->version != 0) {
74 ESP_LOGE(TAG, "image has invalid signature version field 0x%08x (image without a signature?)", sig_block->version);
75 return ESP_FAIL;
76 }
77
78 ESP_LOGD(TAG, "Verifying secure boot signature");
79
80 bool is_valid;
81 is_valid = uECC_verify_antifault(signature_verification_key_start,
82 image_digest,
83 ESP_SECURE_BOOT_DIGEST_LEN,
84 sig_block->signature,
85 uECC_secp256r1(),
86 verified_digest);
87 ESP_LOGD(TAG, "Verification result %d", is_valid);
88
89 return is_valid ? ESP_OK : ESP_ERR_IMAGE_INVALID;
90 }
91
92 #endif // CONFIG_SECURE_SIGNED_APPS_ECDSA_SCHEME
93
